Frameworks and Libraries

General

Bulma: Free, open source, and modern CSS framework based on Flexbox

UIkit

Bootstrap

Foundation

Semantic UI

Pure

Atomic and utility

Tailwind CSS - A Utility-First CSS Framework for Rapidly Building Custom Designs

Headless UI

Windi CSS

Tailwind CSS Components

GitHub - saadeghi/daisyui: ⭐️ ⭐️ ⭐️ ⭐️ ⭐️  Tailwind Components

TACHYONS - Css Toolkit

Atomic CSS

Challenging CSS Best Practices - Smashing Magazine

Classless

MVP.css - Minimalist stylesheet for HTML elements

andybrewer/mvp

new.css

xz/new.css

oxalorg/sakura

Drop-in Minimal CSS

dohliam/dropin-minimal-css

Plume CSS - A Pure CSS Micro-Framework

felippe-regazio/plume-css

Bahunya

Kimeiga/bahunya

NES.css

nostalgic-css/NES.css

Others

Milligram - A minimalist CSS framework

milligram/milligram

chota - A micro CSS framework

jenil/chota

Grommet

grommet/grommet

blocks.css

thesephist/blocks.css

css-doodle

css-doodle/css-doodle

CSS Challenge Ⅱ - a Collection by yuanchuan on CodePen